Leak detection device

ABSTRACT

A leak detection device operable to measure fluid leaks in an element to be tested that is positioned in a first enclosure. In one example, a measuring module is positioned in a second enclosure and connected to the first enclosure and the element to be tested by an aeraulic connection. At least one of the first enclosure and the measuring module are thermally insulated using an insulating material.

CROSS-REFERENCE TO RELATED APPLICATIONS

This utility patent application claims priority benefit to French PatentApplication number FR20000800 filed Jan. 28, 2020 the entire contents ofwhich are incorporated herein by reference.

TECHNICAL FIELD

The present invention relates to the field of devices for detectingleaks (or for measuring tightness) on parts to be tested, moreparticularly leak detection devices based on the measurement of aphysical quantity, such as a pressure or a flow rate, relative to a leaklevel.

BACKGROUND

Indeed, it is necessary to be able to check the integrity of partsand/or to check whether the latter have a leak and to be able toquantify it. The products/parts to be tested are for example electronicappliances, mechanical parts, containers, etc., tightness being acritical characteristic in the context of products subject to externalstress and/or required to meet particular operating requirements, suchas that of being impermeable to liquids (such as water) or of not havingleaks liable to degrade the performances of the product, etc.

Furthermore, the method “by pressure variation” (or variation of arelated physical quantity, such as the flow rate) is the quickest andmost economical method. Indeed, in the pressure variation method, theobject to be tested is subjected to a controlled pressure variation,i.e. a pressure variation is applied to an internal volume of the object(so-called direct method) or to a closed volume surrounding the objectto be tested (so-called indirect method). Then, after a defined time,the pressure is measured again, if the object has a leak, then thepressure measured is different from the initial pressure.

The pressure variation measured by the pressure sensor of the devicethus makes it possible to check the tightness of an object and quantifya leak if the object is not impermeable.

It is thus critical to have a pressure (or flow rate) sensor capable ofmeasuring small pressure (or flow rate) variations and thus detect smallleaks.

Nevertheless, the measurements made with this type of device can beinfluenced by environmental factors or intrinsic factors to said device.These factors are all the more impacting when it is sought to determinelow leak levels on objects having large volumes, such as electric,particularly motor vehicle, batteries. Indeed, in the case of largevolumes and low leak levels, the variations related to the temperatureof the environment or of the element to be tested can give rise topressure variations of an order of magnitude substantially equal to thelevel of the leaks that it is sought to detect.

SUMMARY

Thus, research and tests were carried out by the holder to propose aleak detection device having an enhanced sensitivity and enablingsuperior repeatability in leak detection, while enhancing the level ofdetectability of said leaks.

The invention is thus a novel leak detection device comprising:

at least one enclosure capable of receiving an element to be tested;

a module for measuring at least one physical quantity relative to a leaklevel;

at least one aeraulic connection connecting said at least one enclosureto said measuring module;

Characterised in that said at least one enclosure and/or said module arethermally insulated.

Thermally insulating at least the volume wherein the leak detection isperformed and/or the measuring module makes it possible to avoidenvironmental parameters, such as rapid temperature variations liable toarise in the immediate environment of said detection device, and makesit possible to enhance the level of sensitivity of the measuring module(therefore the level of detectability of the leaks). Indeed, as the leakdetection is based on a pressure measurement depending particularly onthe temperature (therefore on the surrounding thermal noise), enhancingthe inertia and thermal decoupling of the volume used as a basis fordetermining the leak level enhances the quality and the repeatability ofa leak detection.

It will be noted that, in the case of a leak detection on an elementhaving a large volume, it is advantageous to thermally insulate theenclosure receiving the element to be tested, otherwise it isadvantageous to thermally insulate the measuring module. However, if itis sought to optimise the detection of a leak, it is very advantageousto insulate both the enclosure receiving the element to be tested andthe measuring module.

According to a possible feature, the thermal insulation of saidenclosure and/or said measuring module is carried out by means of amaterial having a thermal conductivity less than 0.05 W.m⁻¹.K⁻¹ at 20°C., and preferably less than 0.03 W.m⁻¹.K⁻¹ at 20° C., and even morepreferably less than 0.01 W.m⁻¹.K⁻¹ at 20° C.

According to a further possible feature, the device comprises at leasttwo enclosures, a thermally insulated enclosure, or first enclosure,capable of receiving the element to be tested and a further thermallyinsulated enclosure, or second enclosure, housing the measuring module.

According to a further possible feature, said at least one enclosurecapable of receiving an element to be tested also houses the measuringmodule.

According to a further possible feature, the first enclosure is housedin the second enclosure, the volume between the two enclosures definingan intercalated volume. Generally, an intercalated volume is filled withgas, such as an inert gas or air.

It can be advantageous for questions of size to house one of theenclosures in the other, for example the second enclosure in the first.It will be noted that in this case, the second enclosure is notnecessarily thermally insulated, the first enclosure thermallyinsulating, on its own, the element to be tested and the measuringmodule from the outside.

According to a further possible feature, the device is at leastpartially delimited by an outer wall, said enclosure of said measuringmodule, or second enclosure, being surrounded by said at least one outerwall, the volume between said at least one wall and said enclosure ofthe module defining an intercalated volume.

It will be noted that the presence of an intercalated volume filled witha gas or air makes it possible to increase the thermal decouplingbetween the enclosure(s) receiving the part to be tested and/or themeasuring module and the external environment.

According to a further possible feature, the device comprises aventilation device configured to agitate a gas, preferably inert, or airin an intercalated volume (of which at least one of the intercalatedvolumes mentioned above).

Said ventilation device particularly makes it possible to prevent thecreation of hot spots and/or thermal bridges between the enclosure(s)and outside the detection device.

According to a further possible feature, the ventilation device isdisposed in an intercalated volume (more particularly at least one ofthe intercalated volumes mentioned above).

Despite the fact that the ventilation device produces heat, thisarrangement of said ventilation device, surprisingly, does not degradethe thermal insulation of the enclosure(s) and makes it possible tooptimise the size of the leak detection device.

According to a further possible feature, at least one enclosurecomprises a double wall configured so that the volume between said twowalls is depressurized.

This structure of the enclosure makes it possible to thermally insulatethe inside of the enclosure from the outside, indeed, the thermalconductivity of the gas (or air) between the two walls decreases withthe pressure thereof. The device according to the invention can thuscomprise a vacuum pump configured to decrease the pressure of said gas(or of the air) until the thermal conductivity of said gas (or of theair) is less than 0.05 W.m⁻¹.K⁻¹ at 20° C., and preferably less than0.03 W.m⁻¹.K⁻¹ at 20° C., and even more advantageously less than 0.01W.m⁻¹.K⁻¹ at 20° C.

According to a further possible feature, the measuring module comprisesat least one pressure sensor.

It will be noted that the measuring module can also comprise one or morevalves, one or more electronic circuits, for example for the monitoringand management of valves, measurement, etc.

According to a further possible feature, said sensor is a differentialpressure sensor.

According to a further possible feature, said enclosure receiving theelement to be tested comprises one or more cavities capable of receivingan element to be tested and a reference element.

It will be noted that if the leak detection is carried out by the directmethod, a single cavity capable of receiving the test and referenceelements is sufficient. Whereas if the leak detection is carried outwith the indirect method, it is necessary to have two separate cavitiesin said enclosure, each of the cavities respectively receiving anelement to be tested and a reference element. In the case where thereare two cavities in said enclosure, it is advantageous that the cavitiesare thermally insulated from one another.

According to a further possible feature, said aeraulic connectioncomprises at least two conduits connecting said cavities or saidelements disposed in said at least one enclosure to the differentialpressure sensor, said conduits being substantially symmetrical.

Indeed, in the case where leak detection is carried out by comparingbetween an element to be tested and a reference element, it ispreferable to limit the influence of parameters capable of modifying themeasurement, such as a difference in length, diameter, etc. between saidconduits of the aeraulic connection.

According to a further possible feature, said at least one aeraulicconnection is thermally insulated.

It is advantageous to limit the influence of the temperature of theexternal environment on the air circulating in the aeraulic connections,this is all the more relevant as the aeraulic connection is long.

According to a further possible feature, said at least one aeraulicconnection comprises a thermally insulating sheath, said sheathcomprising a material wherein the thermal conductivity is less than 0.05W.m⁻¹.K⁻¹ at 20° C., preferably less than 0.03 W.m⁻¹.K⁻¹ at 20° C., andeven more advantageously less than 0.01 W.m⁻¹.K⁻¹ at 20° C.

According to a further possible feature, said enclosure receiving theelement to be tested comprises a single cavity capable of receiving theelement to be tested and a reference element.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be understood better, and other aims, details,features and advantages thereof will emerge more clearly in the courseof the following description of specific embodiments of the invention,given merely by way of illustration and not limitation, with referenceto the appended drawings, wherein:

FIG. 1A is a schematic representation of a leak detection deviceaccording to a first embodiment of the invention.

FIG. 1B is a representation of an alternative embodiment of the devicein FIG. 1A.

FIG. 2 is a schematic representation, in a perspective, partiallycut-away view, of a leak detection device according to a secondembodiment of the invention.

FIG. 3 is a very schematic representation of a leak detection deviceaccording to a third embodiment of the invention.

DETAILED DESCRIPTION

FIG. 1A is a schematic representation of a leak detection device 1according to a first embodiment of the invention.

Said leak detection device 1 thus comprises:

an enclosure 3, or first enclosure, capable of receiving an element tobe tested;

a detection or measurement module 5 for measuring at least one physicalquantity relative to a leak level, said module 5 comprising at least onepressure sensor (not shown), such as a differential pressure sensor;

at least one aeraulic connection 7 connecting said enclosure 3 to saiddetection module 5.

Said measuring module 5 can also comprise valves, an electronic controland/or measurement board, a coupling (not shown) with a pressurised airinlet, etc.

Said aeraulic connection 7, by means of said valves and said coupling,enables the detection unit 5 to vary the pressure in the element to betested (direct method) and connect said pressure sensor to the internalvolume of the element to be tested.

In the example shown in FIG. 1A, the pressure variation is applied to aninternal volume of the part to be tested, but the detection of a leakcould also be performed on a volume surrounding the part to be tested.

In the example shown in FIG. 1A, the enclosure 3 is configured toreceive two parts, one element to be tested 6 a and one referenceelement 6 b. More particularly, the enclosure 3 thus comprises a singlecavity 3 a wherein the element to be tested 6a and the reference element6 b are disposed, side by side.

The aeraulic connection 7 comprises, for its part, two conduits 7 a and7 b, said conduits 7a and 7b respectively connecting the part to betested 6a and the reference part 6 b to said pressure sensor of themodule 5 (but also to the enclosure 3).

The enclosure 3, for its part, is thermally insulated, the termthermally insulated denotes an enclosure having a sufficient thermalinsulation and/or inertia such that the leak detection is not impactedby a temperature variation in the environment of said device.

Said leak detection device 1 also comprises a further enclosure 13, orsecond enclosure. The detection module 5, and more particularly thepressure sensor, is disposed in the enclosure 13 (the other elements ofsaid module, valves, electronics, etc. can be disposed outside saidenclosure 13).

The second enclosure 13, similarly to the first enclosure 3, isthermally insulated.

The thermal insulation of the first and/or the second enclosure 3 and 13is carried out by means of a material having a thermal conductivity lessthan 0.05 W.m⁻¹.K⁻¹ at 20° C., and preferably less than 0.03 W.m⁻¹.K⁻¹at 20° C., and even more advantageously less than 0.01 W.m⁻¹.K⁻¹ at 20°C. The enclosures 3 and 13 comprise for example one or more walls madeof a material of this type.

Moreover, the device 1 comprises a housing 14 wherein the secondenclosure 13 (and therefore the measurement module 5) are disposed, thehousing 14 including one or more outer or external walls delimiting apart of the device 1 from the outside. The volume located between thesecond enclosure 13 and this outer wall defines an intercalated volumewherein a ventilation device 15 is disposed. Said ventilation device 15is configured to ensure a movement (or agitation) of the air or gas insaid intercalated volume.

The leak detection device 1 can also comprise a screen 17 located on theouter wall of the housing 14 and serving to display the results of theleak detection carried out on the element to be tested.

It will be noted, furthermore, that the aeraulic connection 7 ispreferably thermally insulated, the conduit(s) 7 a, 7 b are made of athermally insulating material or comprise a sheath, mounted on theconduit(s), made of a thermally insulating material. Said materialenabling the thermal insulation of said aeraulic connection 7 has athermal conductivity less than 0.05 W.m⁻¹.K⁻¹ at 20° C., and preferablyless than 0.03 W.m⁻¹.K⁻¹ at 20° C., and more preferably less than 0.01W.m⁻¹.K⁻¹ at 20° C.

FIG. 1B, for its part, illustrates a leak detection device 1′ which isan alternative embodiment of the device 1 shown in FIG. 1A. Identicalelements are indicated by means of the same references and will not bedescribed again.

The device 1′ comprises an enclosure 3′ entirely similar to theenclosure 3 described above, the only difference being that the lattercomprises two cavities 3 a′ and 3 b′ intended to respectively receive anelement to be tested 6 a and a reference element 6 b.

Indeed, when the leak detection method is carried out indirectly, it isthen necessary to have two separate and mutually impermeable cavities 3a′ and 3 b′. Advantageously, the cavities 3 a′ and 3 b′ are alsothermally insulated in relation to one another (and also in relation tothe outside).

In further alternative embodiments not shown of the devices 1 and 1′,only the enclosure receiving the element to be tested or the measuringmodule is thermally insulated from the outside.

FIG. 2 is a schematic representation, in a perspective view, of a leakdetection device 201 according to a second embodiment of the invention.The same elements bear the same references as those described above andtherefore will not be described again.

The device 201 in FIG. 2 therefore comprises a housing 14′ which housesthe measuring module 5, an enclosure 203, or first enclosure, configuredto receive an element to be tested 6 a and a reference element 6 b, andan aeraulic connection 7 connecting the measuring module to saidelements 6 a and 6 b.

The first enclosure 203 and/or the housing 14′ can be thermallyinsulated like the enclosures 3 and 13 described above. In the casewhere the housing 14′ is thermally insulated, it then acts as anenclosure 213, or second enclosure (the second enclosure 213 thereforehouses/surrounds the first enclosure 203 and the measuring module 5).

It will be noted that the volume defined between the second enclosure213 and the first enclosure 203 defines an intercalated volume wherein aventilation device 15 can be disposed.

As above, the device 201 can be provided with a screen 17 for displayingthe result of the leak detections carried out on the elements to betested.

In an alternative embodiment not shown, the first enclosure 203comprises two separate cavities, preferably thermally insulation inrelation to one another (particularly advantageous alternativeembodiment for leak detection by the indirect method).

FIG. 3 is a schematic representation of a leak detection device 301according to a third embodiment of the invention. The same elements bearthe same references as those described above and therefore will not bedescribed again.

The device 301 thus comprises a housing 314 which houses:

a measuring module 5;

an enclosure 303, or first enclosure, configured to receive an elementto be tested 6 a;

an enclosure 313, or second enclosure, wherein the measurement module 5is housed and which is disposed at a distance from the first enclosure303;

an enclosure 304, or third enclosure, which is disposed in the housing314 and which is configured to receive a reference element 6 b;

an aeraulic connection 7 connecting the measuring module 5 to saidenclosures 303 and 304.

As above, the enclosures 303, 304 and/or 313 can be thermally insulatedlike the enclosure described above (particularly in the firstembodiment).

Said device 301 also comprises, as in the other embodiments described, aventilation device 15 configured to ensure a movement (or agitation) ofthe air or gas in said intercalated volume.

In alternative embodiments of the first, second and third embodiment notshown, the enclosure(s) housing the measuring module, the element to betested and/or the reference element, comprise a double wall. Said doublewall includes two walls at a distance from one another. Moreparticularly, said double wall of the enclosure is configured such thatthe volume between said two walls is depressurized, for example by meansof a vacuum pump.

That is to say that the device according to the invention comprises forexample a vacuum pump configured to reduce the pressure of the gas, suchas air or an inert gas, located between the two walls of said enclosure.The pressure of the gas located between the two walls of the enclosureis then lowered until the thermal conductivity of said gas is less than0.05 W.m⁻¹.K⁻¹ at 20° C., and preferably less than 0.03 W.m⁻¹.K⁻¹ at 20°C., and more preferably less than 0.01 W.m⁻¹.K⁻¹ at 20° C.

What is claimed is:
 1. A leak detection device comprising: at least oneenclosure operable to receive an element to be tested; a measuringmodule operable to measure at least one physical quantity in relation toa leak level; at least one aeraulic connection connecting said at leastone enclosure to said measuring module; characterized in that at leastone of said at least one enclosure or said module further comprisethermal insulation and are thermally insulated.
 2. The device accordingto claim 1, wherein the thermal insulation of said at least one of saidat least one enclosure or said measuring module further comprises amaterial having a thermal conductivity less than 0.05 W.m⁻¹.K⁻¹ at 20°C.
 3. The device of claim 2, wherein the thermal insulation comprises amaterial having a thermal conductivity less than 0.03 W.m⁻¹.K⁻¹ at 20°C.
 4. The device according to claim 1, wherein the at least oneenclosure comprises a thermally insulated first enclosure operable toreceive the element to be tested and a thermally insulated secondenclosure operable to house the measuring module.
 5. The deviceaccording to claim 4, further comprising a housing including an outerwall surrounding said second enclosure, the outer wall and the secondenclosure defining an intercalated volume.
 6. The device according toclaim 5 further comprising a ventilation device operable to agitate agas in the intercalated volume.
 7. The device according to claim 1,wherein said at least one enclosure operable to receive the element tobe tested further houses the measuring module.
 8. The device accordingto claim 1, wherein the at least one enclosure comprises two wallsdefining a depressurized volume between said two walls.
 9. The deviceaccording to claim 1, wherein the measuring module comprises at leastone pressure sensor.
 10. The device according to claim 9, wherein saidat least one pressure comprises a differential pressure sensor.
 11. Thedevice according to claim 9 wherein said at least one enclosurecomprises one or more cavities operable to receive the element to betested and a reference element.
 12. The device according to claim 11,wherein the one or more cavities comprises a first cavity and a secondcavity, and wherein the at least one aeraulic connection comprises atleast two conduits connecting said first and second cavities to thepressure sensor, said at least two conduits being substantiallysymmetrical.
 13. The device according to claim 11, wherein the one ormore cavities comprises a first cavity and a second cavity, and whereinthe at least one aeraulic connection comprises at least two conduitsconnecting the element to be tested and the reference element to thepressure sensor, the at least two conduits being substantiallysymmetrical.
 14. The device according to claim 1, wherein said at leastone aeraulic connection is thermally insulated.
 15. A leak detectiondevice comprising: at least one enclosure operable to receive an elementto be tested; a measuring module operable to measure a physical quantityof a liquid leak level; at least one aeraulic connection connecting theat least one enclosure and to said measurement module; and thermalinsulation applied to at least one of the at least one enclosure or themeasuring module operable to thermally insulate the at least oneenclosure or the measuring module, the thermal insulation including amaterial having a thermal conductivity less than 0.05 W.m⁻¹.K⁻¹ at 20°C.
 16. The leak detection device of claim 15 wherein the at least oneenclosure comprises a first enclosure having at least one cavityoperable to receive the element to be tested and a second enclosureoperable to receive the measuring module, the first enclosure and secondenclosure having the thermal insulation.
 17. The leak detection deviceof claim 16 wherein the second enclosure is positioned in outersurrounding relation to the first enclosure defining an intercalatedvolume between the second enclosure and the first enclosure; the devicefurther comprising a circulation device positioned within the secondenclosure and operable to circulate a fluid positioned in theintercalated volume.
 18. The leak detection device of claim 16 furthercomprising: a housing surrounding the second enclosure defining aintercalated volume between the second housing and the second enclosure;and a circulation device positioned within the housing operable tocirculate a fluid positioned in the intercalated volume.
 19. The leakdetection device of 16 wherein the first enclosure at least one cavitycomprises a first cavity for receipt of the element to be tested and asecond cavity for receipt of a reference element, the aeraulicconnection connected to the first enclosure, the element to be testedand the reference element.